This disclosure relates generally to electric machines. More specifically, this disclosure relates to cooling of belt-driven vehicle electrical power generators.
Underhood airflow in a vehicle is from the front of the vehicle to the rear due substantially to the action of radiator cooling fans disposed at the front of the vehicle. In contrast, however, cooling air typically enters an electric machine, for example, an alternator, at or near the rear of the alternator. The air flows through the alternator to the front of the alternator, being heated by the alternator components. The heated air is expelled from the alternator, combines with the underhood airflow, and is carried back to the rear of the alternator where at least a portion of the heated air is recirculated through the alternator. Depending on the alternator configuration, as much as 30-35% of the heated air is recirculated through the alternator, raising the temperature of the cooling air entering the alternator 20-30 degrees C. The increased temperature of the cooling air results in a reduction of the cooling capability of the air and may have a negative impact on alternator performance.